1. Field of the Invention
The present invention relates to an apparatus and method for identifying the liquid type of a gasoline.
2. Description of Related Art
Conventionally, the exhaust gas of a car contains pollutants such as unburned hydrocarbon (HC), an NOx gas and an SOx gas. In order to reduce the pollutants, therefore, S in a gasoline is removed for the Sox or unburned HC is burned by a catalyst, for example.
More specifically, as shown in FIG. 28, a car system 100 takes air in through an automatic element (filter) 102 and feeds the air into an engine 106 through an air flow sensor 104. Moreover, the car system 100 feeds a gasoline in a gasoline tank 108 into the engine 106 through a gasoline pump 110.
Based on the result of the detection of an A/F sensor 112, the injection of the fuel in the engine 106 is controlled by a fuel injection control device 114 in order to have a predetermined theoretical air fuel ratio.
For an exhaust gas fed from the engine 106, hydrocarbon (HC) in the exhaust gas is burned by a catalytic device 116 and is then discharged as the exhaust gas through an oxygen concentration sensor 118.
In such a car system, gasolines sold all over the world include various gasolines having different distillation characteristics (different easinesses of evaporation) as shown in FIG. 29.
More specifically, FIG. 29 shows the distillation characteristics of gasolines, illustrating a relationship between a percentage and a temperature, and an axis of abscissa of 50% (T50) indicates a temperature at which 50% of each gasoline evaporates, for example.
As shown in FIG. 29, for example, a gasoline A2 represents the heaviest gasoline (which rarely evaporates) and a gasoline No. 7 represents the lightest gasoline (which easily evaporates) with respect to a standard gasoline No. 3.
As shown in the following Table 1, accordingly, in the case in which the heavier gasoline A2 is used in a car regulated to have a theoretical air fuel ratio with the standard gasoline No. 3, for example, the amount of HC in an exhaust gas is small and a torque becomes insufficient, particularly, at time of engine starting in which an engine and a catalytic device do not warm up.
To the contrary, in the case in which the lighter gasoline No. 7 is used, the torque is insufficient and the theoretical air fuel ratio is exceeded. As a result, the amount of the HC in the exhaust gas is increased, particularly, at time of the engine starting in which the engine and the catalytic device do not warm up, which is not preferable because an environment is greatly influenced.
TABLE 1RegulatedUsedExhaust gasgasolinegasolineTorque(HC)No. 3No. 3◯◯No. 3A2X◯No. 3No. 7◯X
The present inventors have proposed a fluid identifying method in Japanese Laid-Open Patent Publication No. Hei 11(1999)-153561 (particularly see paragraphs (0042) to (0049)) (which will be hereinafter referred to as “Patent Document 1”). In this method, a heating member is caused to generate heat by carrying electricity, a temperature detector is heated through the heat generation, a heat transfer from the heating member to the temperature detector is thermally influenced through a fluid to be identified, and the type of the identified fluid is distinguished based on an electrical output corresponding to the electric resistance of the temperature detector. In this method, the electricity is periodically carried to the heating member.
In the fluid identifying method, however, it is necessary to periodically carry the electricity to the heating member (in a multipulse). For this reason, a long time is required for the identification so that it is hard to identify a fluid instantaneously. In this method, moreover, it is possible to identify a fluid based on a central value for substances having very different characteristics such as water, air and oil. However, it is hard to identify the gasolines having very close characteristics to each other accurately and rapidly.
Conventionally, a so-called high-octane gasoline having an octane value increased such as lead or a benzene based compound, or a gasoline into which an antiknocking agent such as methyl tertiary butyl ether or methyl-t-butyl ether (MTBE) is mixed has been used for a car or the like in order to prevent knocking, for example.
However, there is a possibility that the lead, the benzene based compound or the like might influence an environment. Moreover, it is said that the methyl tertiary butyl ether or the methyl-t-butyl ether (MTBE) is cancer-causing. For this reason, it has been desired to develop the high-octane gasoline and an antiknocking agent in place of the antiknocking agent constituted by the methyl tertiary butyl ether or the methyl-t-butyl ether (MTBE).
Therefore, it has been proposed that alcohol, for example, ethanol is added, as the antiknocking agent, in an amount of approximately 10 to 15% to a gasoline.
However, such ethanol is added so that a torque is reduced. Therefore, it is necessary to cause the torque to be constant by excessively adding a gasoline corresponding to the amount of addition of the ethanol.
In the case in which the alcohol is contained in the gasoline in the identification of the liquid type of the gasoline as described above, furthermore, liquid type identification data are influenced. As a result, it is hard to identify the liquid type accurately and rapidly.
For this reason, it has been desired to detect the concentration of alcohol contained in a gasoline.
As a method for detecting the concentration of alcohol, conventionally, an optical alcohol concentration measuring apparatus for detecting the concentration of alcohol by utilizing the refractive index of a light has been disclosed as in Japanese Laid-Open Patent Publication No. Hei 5 (1993)-223733 (see paragraphs (0017) to (0030) and FIG. 1) (whichwillbehereinafter referred to as “Patent Document 2”).
More specifically, in an optical alcohol concentration measuring apparatus 200 in the Patent Document 2, as shown in FIG. 30, a light which is transmitted from a first light emitting portion 202 through a liquid and has a wavelength with such a property that an absorption into alcohol such as ethanol is hard to perform is received by a first light receiving portion 204 and a detection signal corresponding to an alcohol concentration in the liquid is output.
Moreover, a light, which is transmitted from a second light emitting portion 206 through the liquid and has another wavelength with such a property that the absorption into the alcohol is easy, is received by a second light receiving portion 208 and a detection signal corresponding to the alcohol concentration in the liquid is output.
Consequently, in a measuring portion 210, the detection signal sent from the first light receiving portion 204 is compared with the detection signal sent from the second light receiving portion 208 and the alcohol concentration in the liquid is measured.
As described in “Electrostatic Capacitance Type Alcohol Concentration Sensor” (see Norio Sanma, Ikuo Hayashi, Ichiro Hosotani, The Society of Automotive Engineers of Japan, Annual Congress Preliminary Printing Collection 936, 1993-10, pages 257 to 260) (which will be herein after referred to as “Non-Patent Document 1”), conventionally, an electrostatic capacitance type alcohol concentration sensor has been proposed.
In the Non-Patent Document 1, there has been proposed a method for measuring the concentration of methanol mixed into a gasoline from an electrostatic capacitance between electrodes at an oscillation frequency by utilizing a difference in a specific inductive capacity between the gasoline and the methanol (the gasoline has a specific inductive capacity of 2 and the methanol has a specific inductive capacity of 33.6), thereby detecting the concentration of the methanol.
An electrostatic capacitance type alcohol concentration sensor 300 according to the Non-Patent Document 1 has such a structure that an outer electrode 304 and a center electrode 306 are attached through an insulating resin 308 into a housing 302 as shown in FIG. 31.
Since the optical alcohol concentration measuring apparatus according to the Patent Document 2 utilizes a transmitted light, however, it is easily influenced by the composition of a gasoline. For example, in the case in which the gasoline is not transparent due to an impurity, moreover, a measurement cannot be carried out or an accurate measurement cannot be performed.
In the electrostatic capacitance type alcohol concentration sensor utilizing an electrostatic capacitance according to the Non-Patent Document 1, furthermore, a moisture is apt to enter alcohol and a short circuit is generated between electrodes if the moisture, an electrolyte or the like is present between the electrodes. Accordingly, an insulating treatment for the surface of the electrode is required and a structure thereof is complicated.
In this case, an electrostatic capacitance Cs is expressed in the following equation.Cs=ε0(S/D) (ε ra(α/100)+εrg(1−α/100))  Equation 1
Herein, S represents an opposed area of an electrode, D represents a distance between the electrodes, ε0 represents a specific inductive capacity of a vacuum (8.854 E−12 F/m), ε ra represents a specific inductive capacity of alcohol, ε rg represents a specific inductive capacity of a gasoline, and a represents an alcohol concentration (%).
As is apparent from the Equation, accordingly, it is preferable to increase the opposed area of the electrode to increase the electrostatic capacitance Cs in order to obtain the excellent results of the measurement. When the opposed area of the electrode is thus increased, however, the size of the electrostatic capacitance type alcohol concentration sensor itself is increased as in the Non-Patent Document 1. For this reason, handling, an application to a car and the like are also restricted in respect of a design.
In the electrostatic capacitance type alcohol concentration sensor according to the Non-Patent Document 1, furthermore, the sensor is to be connected to a body of a gasoline piping in a car or the like, for example. However, a noise such as an electromagnetic wave or the like which is generated from the body influences an alcohol-concentration detecting circuit so that an accurate measurement cannot be carried out.
For this reason, an insulating structure is added to the connecting portion of the sensor and the piping or the whole large-sized sensor is to be put in an insulating shield container. Consequently, the apparatus becomes complicated and large-sized.
In consideration of such circumstances, it is an object of the present invention to provide an apparatus and method for identifying the liquid type of a gasoline which can identify the type of a gasoline accurately and rapidly by detecting an alcohol concentration in each of gasolines having different distillation characteristics and various compositions and correcting liquid type identification data on the gasolines based on a result.
Moreover, it is an object of the present invention to provide an apparatus for identifying the liquid type of a gasoline, comprising an alcohol concentration detecting device which is small-sized and compact, can be installed everywhere and can have the degree of freedom of a design, has an excellent insulation between electrodes and is not influenced by a moisture, can carry out shielding in order not to be influenced by an electromagnetic wave generated from a body of a car or the like, and furthermore, can execute an accurate measurement for the alcohol concentration, and a method for identifying the liquid type of a gasoline.
Furthermore, it is an object of the present invention to provide an apparatus and method for identifying the liquid type of the gasoline of a car using the apparatus and method for identifying the liquid type of a gasoline.
In addition, it is an object of the present invention to provide an apparatus and method for reducing the exhaust gas of a car using the apparatus and method for identifying the liquid type of a gasoline which can efficiently reduce the exhaust gas and can enhance a mileage.